extisp.icio.us text gives you a random textual scattering of a user's tags, sized according to the number of times that they've used each of them, and leaves you to draw your own insights from the overlapping entrails.
Using RhNav - Rhizome Navigation I wrote a data aggregator for Technorati's API. The first result is a video which visualizes blog domains by analysing Technorati's Cosmos (the blogs which link to a particular URL). The video is a screencast of RhNav fetc